Critically ill older adults are profoundly inactive while in ICU; therefore, activity promotion after ICU discharge is crucial for recovery. Up to 90% of older ICU survivors are discharged with at least one “geriatric syndrome” (e.g., delirium, cognitive impairment). Poor executive function, a subdomain of cognition, predicts institutionalization (i.e., discharge to long-term care facility).We calculated a ratio of daytime-to-nighttime activity among older ICU survivors during the early post-ICU transition period. We hypothesized that higher daytime-to-nighttime activity ratios (i.e., proportionally higher activity during daytime hours) would be associated with better executive function. We enrolled 30 older adults who were functionally independent prior to hospitalization, mechanically ventilated while in ICU, and within 24-48 hours post-ICU discharge. Actigraphy recorded daytime activity (mean activity counts/minute, 06:00 AM-21:59 PM) and nighttime activity (mean activity counts/minute, 22:00 PM-05:59 AM). We calculated the daytime-to-nighttime activity ratio by dividing daytime activity by nighttime activity. We assessed cognitive flexibility using the NIH Toolbox Cognition Battery Dimensional Change Card Sort Test (DCCST: fully-corrected T score adjusted for age, sex, race/ethnicity, and education). Regression analyses examined the association between the daytime-to-nighttime activity ratio and DCCST scores, with adjustment for two covariates (ICU severity of illness score, grip strength).


Additional author(s): Cindy Munro, Zhan Liang